The latest Firefox adds native PDF support. That's the biggest feature in the release, in addition to bug fixes and improvements for developers.

Firefox for Windows, Mac and Linux introduces a built-in browser PDF viewer that allows you to read PDFs directly within the browser, making reading PDFs easier because you don't have to download the content or read it in a plugin like Reader. For example, you can use the PDF viewer to check out a menu from your favorite restaurant, view and print concert tickets or read reports without having to interrupt your browsing experience with extra clicks or downloads.